Question

Consider the following two statements:
(A) Linear momentum of a system of particles is zero.
(B) Kinetic energy of a system of particles is zero.

• A. A implies B and B implies A.
• B. A does not imply B and B does not imply A.
• C. A implies B but B does not imply A.
• D. B implies A but A does not imply B.

Answer 1

The correct option is D

B implies A but A does not imply B.

If Linear momentum of particles is zero then do you all the particles have to be at rest in order to achieve this?
Linear momentum is a vector quantity and I thinkyou now understand that a particle of 1 kg moving with 1 m/s towards rightwards and 1 kg moving with 1 m/s towards leftwards as a system will have zero linear momentum.
Whereas if the particles are not moving at all i.e., all the particles of a system are at rest, absolutely implies that Linear momentum of system of particles is zero.
Therefore B implies A but A does not implies B.